Demography and pathology of a pacific walrus (Odobenus rosmarus divergens) mass-mortality event at Icy Cape, Alaska, September 2009

The objective of this paper is to report on the demography and pathology of 131 Pacific walruses ( Odobenus rosmarus divergens ), primarily calves, found dead on the northwest coast of Alaska in September 2009. The walrus carcasses extended over approximately 120 km, but most were found where walruses had hauled out for several days on the beach at Icy Cape. The remote location and severe weather made access to the site difficult and limited the number and extent of necropsies. A total of 71 carcasses were examined: nine were necropsied, and 62 were classified externally for age, gender, blubber depth, and other parameters. The most likely causes of death were crushing trauma, particularly of the upper thorax, neck and head, or asphyxiation due to being trampled by larger animals.